git_repository_open, given a nonexistent path, trashes pthread_self on macOS/ARM64 #6871
Description
Reproduction steps
#include <git2.h>
#include <pthread.h>
#include <stdio.h>
int main(int argc, char const * const *argv) {
if (argc < 2) {
fprintf(stderr, "Pass a path to a directory for git_repository_open\n");
return 1;
}
char const *path = argv[1];
printf("before git_repository_open: pthread_self: %p\n", pthread_self());
git_repository *repo = NULL;
int err = git_repository_open(&repo, path);
if (err == 0) {
printf("git_repository_open succeeded: %p\n", repo);
} else {
printf("git_repository_open failed: %d\n", err);
}
printf("after git_repository_open: pthread_self: %p\n", pthread_self());
exit(0);
}I'm using the libgit2 from homebrew, but the version Apple ships with Xcode also has the problem:
cc \
-I/opt/homebrew/include \
main.c \
/opt/homebrew/lib/libgit2.a \
/opt/homebrew/lib/libssh2.a \
/opt/homebrew/lib/libcrypto.a \
-lz -liconv \
-framework Security -framework FoundationRunning the test program on /usr succeeds, but on /foo fails:
$ lldb a.out
(lldb) target create "a.out"
Current executable set to '/Users/<me>/.../Libgit2NukesPthreadSelf/a.out' (arm64).
(lldb) r /usr
Process 73772 launched: '/Users/<me>/.../Libgit2NukesPthreadSelf/a.out' (arm64)
before git_repository_open: pthread_self: 0x1fa3fcf40
git_repository_open failed: -1
after git_repository_open: pthread_self: 0x1fa3fcf40
Process 73772 exited with status = 0 (0x00000000)
(lldb) r /foo
Process 73796 launched: '/Users/<me>/.../Libgit2NukesPthreadSelf/a.out' (arm64)
before git_repository_open: pthread_self: 0x1fa3fcf40
git_repository_open failed: -3
Process 73796 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x1925a973c)
frame #0: 0x00000001925a973c libsystem_pthread.dylib`pthread_self + 56
libsystem_pthread.dylib`pthread_self:
-> 0x1925a973c <+56>: brk #0xc473
0x1925a9740 <+60>: cmp x16, x0
0x1925a9744 <+64>: b.ne 0x1925a9750 ; <+76>
0x1925a9748 <+68>: ldp x29, x30, [sp], #0x10
Target 0: (a.out) stopped.
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x1925a973c)
* frame #0: 0x00000001925a973c libsystem_pthread.dylib`pthread_self + 56
frame #1: 0x00000001000020e0 a.out`main + 224
frame #2: 0x0000000192223154 dyld`start + 2476
Expected behavior
git_repository_open should not trash memory
Actual behavior
Pretty sure git_repository_open is trashing memory! At the least, it's somehow triggering pthread_self's internal safety check, probably this one: https://github.com/apple/darwin-libpthread/blob/main/src/inline_internal.h#L177
Version of libgit2 (release number or SHA1)
1.8.1
Operating system(s) tested
macOS Sonoma 14.6.1